The invention relates in general, to protective wearing apparel and in particular to a protective helmet equipped with a cooling gear which is formed by two foils or sheets sealed to each other to form cells receiving a coolant.
While attempting to provide a healthier ambience for people working under exposed physical conditions, the protection of the head is important. The mechanical protection with the helmet is generally satisfactory. The control of the ambient physical conditions is still wanting, however.
Prior art protective helmets are commonly equipped with a head harness ensuring a satisfactory seat of the helmet. Intermediate space forms between the helmet shell and the harness, permitting air to circulate. This provides a certain cooling. At hot working places, such as in foundries, coking plants and also for drivers of sports cars, this cooling is not satisfactory.
A special system for keeping low temperature, to be used on a user's head too, comprises a plastic tempering mixture of various chemicals with a high water content, enclosed in hot-sealed cells formed between flexible sheets. If such a system is worn on the user's body, it may exchange large heat amounts with the ambience, without thereby appreciably changing its initial temperature or mechanical properties. The system may be provided with a permanent filling of the tempering mixture, or with a closable opening for refilling. For wearing on the user's head, the array of sealed cells forms a hood structure which is held in place by a harness (U.S. Pat. No. 3,463,161).
A combination with a mechanical protection of the head is not provided. A use with a conventional protective helmet requires an adjustment of the fittings and prevents the cooling surfaces from applying against the head uniformly.
A prior art cooling vest comprises a waist portion and a hood portion. Both portions are provided with passages for a liquid coolant which is then circulated therethrough and cooled in a unit worn on the user's back. The flow passages are formed by sheets of plastic which are hot-sealed together, and silicone oil is employed as the coolant. In the hood portion, the flow passages are held in their needed shape by a cap-like carrier. On top of the hood portion, a conventional protective helmet is worn having its harness adjusted to a corresponding volume (assignee's periodical Dragerheft 310 January-April 1978, pages 13-24).
With an improper adjustment of the harness, the circulation of the coolant may be obstructed. Because of the harness, the cooling surfaces apply against the head non-uniformly, with the result of an inadequate distribution of the cooling effect. In view of the connections to the cooling unit, the hood portion can hardly be used separately.